Autumn

Autumn is open-source billing infrastructure designed for AI startups that need flexible, usage-based pricing on top of Stripe. It acts as the system of record for subscriptions, usage metering, credits, and feature entitlements, exposed through a minimal API (attach, check, track). Unlike pure metering tools that only handle end-of-month invoicing, Autumn enforces entitlements and feature access in real time, managing subscription state, credit balances, and usage enforcement. This offloads complex billing logic from your codebase into a configurable layer, making pricing changes as simple as configuration updates. Autumn targets AI-native companies that require credit-based models like per-message, per-token, or compute-based billing. It automatically handles plan switching, proration, failed payments, 3DS, race conditions, and refunds. Because billing logic lives in Autumn, your application can query it inline to determine customer entitlements and track usage against balances without building custom infrastructure. Key features include a real-time credit ledger with grants, rollovers, and expiration; feature entitlement gating (boolean and metered); subscription lifecycle management; and billing controls like spend caps and auto top-ups. It integrates with Stripe, Vercel AI SDK, OpenRouter, Convex, RevenueCat, and more. Autumn is open-source and self-hostable, with a hosted cloud version available. Compared to alternatives like Metronome or Chargebee, Autumn offers real-time enforcement and a developer-first API, but requires Stripe as a payment processor. It's best for startups that want to move fast without rebuilding billing logic from scratch.